Leaf Blowers

I have just purchased a 150BT backpack blower and started using it with the bigger nozzle and when i swtiched to the concentrator smaller nozzle after shutting it down their was a smell like it had run to hot like burning paint i know it was just out of the box but is this normal i have put the right oil mixture and just wanted to know is it ok to use the smaller nozzle, i guess it must be or you would not of put it in the box?